The present invention broadly relates to sewer ventilation systems More particularly the present invention comprises a Sewer Ventilator System for Recreational Vehicles, Boats and the Like that automatically exhausts obnoxious sewer gases and prevents them from entering the vehicle.
Conventional recreational vehicles, camper trailers, boats, and the like are frequently equipped with bathrooms. Self-contained sewage storage tanks are provided for temporarily storing waste. Periodically, the wastes must be emptied to designated dump sites. Sewer gases are generated in the holding tank during this time. Although the overpressure is conventionally vented to atmosphere, when the commode is flushed objectionable gases nevertheless enter the vehicle.
When not connected to a source of water, water must be stored and transported. Since water must be rationed, commodes for such vehicles are designed to minimize the water used during flushing. They generally employ various types of trap-doors to release wastes into the holding tank of the system. There is seldom a water trap for preventing sewer gases from flowing back through the flush valve while it is in the open position. Deodorizing chemicals are used in these sewage holding tanks to help combat foul odors. Also, in the near future all railroad passenger cars will be equipped with self-contained sewer gas holding systems.
Numerous previous U.S. Patents have disclosed methods and apparatuses intended to cope with the odors produced by conventional household and "dry" toilet odors. Person U.S. Pat. No. 3,927,429 addresses a deodorizer to be secured to a conventional household toilet. Goodwin, U.S. Pat. No. 4,025,325 speaks to ventilation of commodes by using a portable filtering unit. Anderson U.S. Pat. No. 4,894,872 concerns outdoor toilets such as those used in remote park areas and some rural areas. This invention provides the holding tank of its system with continuous ventilation. Agelatos U.S. Pat. No. 4,944,045 is a ring shaped ventilation system that is adapted to sense and filter odorous air from conventional household toilets.
Many patents have addressed specific problems encountered by recreational vehicles and their sewer systems. Jacabis U.S. Pat. No. 4,699,207 covers ventilation for the interiors of recreational vehicles. Stewart U.S. Pat. No. 4,710,988 pertains to the design of recreational vehicle commodes and the flushing valve mechanism but, fails to speak to ventilation. Sigler U.S. Pat. No. 4,819,279 addresses vacuum toilet systems in the transfer of waste material. Most recreational vehicles do not have vacuum systems. They are generally gravity fed from the commodes to holding tanks. Mercer U.S. Pat. No. 4,841,578 basically addresses the way chemical is added to RV commodes and holding tanks. Largent-Antos U.S. Pat. No. 4,944,048 addresses a portable holding tank for a recreational vehicle commode. It discloses a removable tank for disposal of the sewage.
Also pertinent to the present disclose are U.S. Pat. Nos.: 2,285,581 issued to Horton; 3,609,772 issued to Howard; 4,108,380 issued to Richardson; 4,704,747 issued to Brubakken; 4,805,660 issued to Antos; 4,867,047 issued Citron; and 4,892,039 issued to Sargent.
Known prior art systems for ventilating conventional recreational vehicle sewage storage tanks are deficient. In particular, an adequate system should operate automatically upon activation of the commode trap door. While such devices must be responsive to their own individual switching mechanisms, optionally they should be capable of automatic triggering when the bathroom lights (or other devices) are activated. When the lights are thereafter turned off, the system should run for a predetermined time and then shut down automatically. Such a device must vent the exhaust gases of the aforementioned tank to the ambient atmosphere by placing suction on the tank to prevent the gases from rising through the trap door of the commode when it is opened.
An adequate system must be easy to install, either during manufacture of the vehicle, or during subsequent retrofitting. The system would not need to operate continuously, and it must avoid draining of the vehicle battery. It should be responsive to the water pump associated with many recreational vehicle toilets. Alternatively, the system could be actuated by a micro switch contacted by the flush lever of the toilet. An acceptable system must therefore respond to any of a variety of electrical inputs, and they must be protectively isolated from one another to prevent mutual interference.